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EARTHQUAKE ›› 2011, Vol. 31 ›› Issue (3): 9-18.

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Study on the Characteristics of Seismic Activity in Southeastern Tibet and Surrounding Areas

ZHANG Lang-ping1, SHAO Zhi-gang1, YAN Rui2   

  1. 1. Institute of Earthquake Science, CEA, Beijing 100036, China;
    2. China Earthquake Network Center, Beijing 100045, China
  • Received:2011-01-21 Revised:2011-04-02 Published:2021-09-09

Abstract: Southeastern Tibet and surrounding area is influenced by the dynamic collision between Indian plate and Eurasian plate, with strong historic seismic activity, including the 1950 Medog-Zayu M8.6 earthquake and the 1951 Dangxiong M8.0 earthquake. In this paper, we first presented the tectonic setting of Southeastern Tibet and surrounding areas firstly and then analysed the characteristics of seismic activity in this region by investigating activities of strong earthquakes and Load/Unload Response Ratio (LURR) time series of segments of the boundaries among active tectonic blocks. In view of the historical seismicity, we found a certain kinematical association between the Andaman arc and the eastern Himalayan system, and the current dynamic environment surrounding the study area is strong seismicly in the Andaman arc and seismicly quiescent in eastern Himalayan system. From the image of seismic activities, earthquakes with magnitude larger than or equal to 6.0 since 1980 have formed a circular seismic gap in southeastern Tibet and surrounding areas, whose spatial distribution is similar to that during the 10 years before the 1950 Medog-Zayu M8.6 earthquake. In terms of the LURR time series for segments of the active tectonic boundaries in the region, the eastern segment of Himalayan boundary is in the high stress state, followed by the Lancang River and Sanjiang tectonic boundaries.

Key words: Image of seismic activities, Southeastern Tibet and surrounding area, Load/unload response ratio, Active tectonic boundary

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